Which of the following is a common physiological response to stress?

The fight-or-flight response is a well-documented physiological reaction to stress, triggered by the body's natural survival mechanisms. When an individual perceives a threat or experiences stress, the autonomic nervous system activates, leading to the release of stress hormones such as adrenaline and cortisol. This response prepares the body to either confront or escape the stressor.

In this state, several physical changes occur: heart rate increases to pump more blood to muscles, pupils dilate for better vision, and energy stores are mobilized to provide quick bursts of strength. This immediate physiological preparedness is critical for survival in threatening situations.

The other responses, while they can be associated with coping mechanisms or states of well-being, do not represent the direct physiological responses that occur during stress. Increased energy levels can result from adrenaline but aren't an immediate or universal physiological response to all stressors. A decrease in heart rate is generally not a response to stress; rather, it can occur during relaxation or calm states. Heightened concentration may happen during acute stress states but is not a physiological response in the same way as the fight-or-flight mechanism.